Dual-stack doesn't require public IPv4 addresses. Since IPv4 is in short supply, providers must still do what they can to conserve them. This means NAT, with appropriate management to not overload any one IP, or CGN if you want to keep public IPv4 (but no longer unique ones) on CPE. Not every customer needs direct IPv4 connectivity without NAT; those that do must pay for it. If those who have it aren't willing to pay, they must give up their public IPv4 address.
That is the most efficient direct IPv4 provisioning concept we have today. Given the history of IPv6 adoption, it's clear that people won't move until they experience pain sticking with IPv4. "On demand" IPv4 isn't currently being done anywhere AFAIK, and since we're abandoning IPv4 it's not likely anyone has that on their priority list. It's not a good policy to go out of your way to make IPv4 users comfortable. IPv4 is going to go away, and the sooner customers get that and go to IPv6, the sooner the pain will stop :) -mel beckman > On Jul 4, 2015, at 6:02 PM, Josh Moore <jmo...@atcnetworks.net> wrote: > > Traditional dual stack deployments implement both IPv4 and IPv6 to the CPE. > Consider the following: > > An ISP is at 90% IPv4 utilization and would like to deploy dual stack with > the purpose of allowing their subscriber base to continue to grow regardless > of the depletion of the IPv4 space. Current dual stack best practices seem to > recommend deploying BOTH IPv4 and IPv6 to every CPE. If this is the case, and > BOTH are still required, then how does IPv6 help with the v4 address > depletion crisis? Many sites and services would still need legacy IPv4 > compatibility. Sure, CGN technology may be a solution but what about > applications that need direct IPv4 connectivity without NAT? It seems that > there should be a mechanism to enable on-demand and efficient IPv4 address > consumption ONLY when needed. My question is this: What, if any, solutions > like this exist? If no solution exists then what is the next best thing? What > would the overall IPv6 migration strategy and goal be? > > Sorry for the length of this email but these are legitimate concerns and > while I understand the need for IPv6 and the importance of getting there; I > don't understand exactly HOW that can be done considering the immediate > issue: IPv4 depletion. > > > Thanks > > Joshua Moore > Network Engineer > ATC Broadband > 912.632.3161
